The present invention relates to an alignment mechanism for a telescopic switch for use for example between a step-up transformer and a generator and particularly relates to alignment mechanisms for the telescopic switch for aligning a circular array of contact fingers of a fixed conductor with a moving conductor.
In land based power generation plants such as nuclear, coal or gas turbine-fired plants, there is typically a connection between a step-up transformer and the generator which includes bus ducts and a telescopic switch. Since there is often variable and substantial distances between the transformer and generator in actual usage at various power plants, e.g., on the order of 100 feet, a bus duct, i.e., a conductor within an enclosure and a telescopic switch are used to connect the transformer and generator. The telescopic switch and bus ducts at opposite ends of the switch must therefore be assembled and fixed to one another in the field to complete the conductive link between the transformer and generator.
A telescopic switch is typically comprised of three circular conductors. Two of the conductors are fixed and a moving conductor is disposed between the fixed conductors. Generally the fixed conductors and a movable conductor are coaxially arranged with the movable conductor intermediate the fixed conductors. Contact fingers are arrayed about near ends of the fixed conductors for contact with the movable conductor. By moving the movable conductor in an axial direction and displacing it inside one of the fixed conductors, the telescopic switch may be moved between open and closed positions. It is singularly important, however, that the circular array of fingers of the fixed conductors all contact the contact area of the movable conductor simultaneously in order to optimize the efficiency of the switch. Thus, field alignment of the fixed and movable conductors is absolutely essential.
In the past, both fixed conductors were supported by two insulators each carried by a housing. The insulators were mounted on a plate and those plates were held in place by four jack screws. This mechanism was composed of a large number of machined parts. When adjustment was required, it was a difficult and long process in order to achieve proper alignment of the conductors due mainly to the complexity of the system. For example, it oftentimes took two to three days to properly adjust and align the conductors relative to one another in the field. Accordingly, there is a need for a field alignment mechanism which would enable adjustment of both fixed conductors relative to the movable conductor to obtain accurate alignment of the rings of contact fingers with the movable conductor just prior to making electrical contact and obtaining the fully closed switch position or conversely when opening the switch.